Anionic synthesis of highly isotactic polystyrene in the presence of lithium hydroxides or lithium alkoxides, and, Controlled 'living' emulsion polymerization of methyl methacrylate by atom transfer radical polymerization.

摘要

Styrene was polymerized by t-butyllithium in the presence of lithium hydroxides (LiOH) or lithium alkoxides in hexane at {dollar}-30spcirc{dollar}C producing mixtures of MEK-insoluble highly isotactic content (mm {dollar}>{dollar} 60%) and MEK-soluble atactic polystyrene. Although the fractions of isotactic polystyrene for the case of lithium t-butoxide (t-BuOLi) are small (mmmm {dollar}<{dollar} 10%) more isotactic polystyrene is formed in the presence of lithium 2-adamantoxide. (mmmm = 20-30%) Surprisingly in the presence of LiOH ({dollar}sim{dollar}1 equiv.) the overall isotactic content is greatly enhanced. (0.90 {dollar}>{dollar} mm {dollar}>{dollar} 0.60) Isotactic polystyrene was also synthesized by polyisopropyrylithium as an initiator in the presence of LiOH or t-BuOLi in hexane at {dollar}-30spcirc{dollar}C or lower. In this case the polymerization proceeds in the micellar-like phase and particularly, in the presence of LiOH at {dollar}-60spcirc{dollar}C, the overall isotactic content (mm) reaches to more than 95%.; Methyl methacrylate is polymerized by radical process using atom transfer radical polymerization (ATRP) in aqueous media. The emulsion polymerization system using potassium persulfate as initiator, sodium dodecyl sulfate as a surfactant, a combination of cupric bromide and cuprous bromide as catalyst yields polymethylmethacrylate (PMMA) with a very narrow molecular distribution. (MWD = 1.1) Thus for the first time, well-controlled PMMA was obtained by radical polymerization in aqueous media.